Pern's northern continent can not be as large as Eurasia. Think about how long it would take on foot to go from Lisbon to Seoul. That would be the same as walking from Tillek to Benden Wyer. Also I can't imagine that with all that space how only 6million people are crowded.

Considering that they can't spread out too much because of Thread and lack of growing areas for crops due to all the mountains, I think I could see what they meant.